The research will continue the characterization of the physical structure and regulation of several genes whose expression is coordinately regulated by cAMP during Dictyostelium development. The first of these genes is the cAMP phosphodiesterase, which we have cloned. This gene will be further characterized and its regulation studied. The second gene is an inhibitor of the cAMP phosphodiesterase and is repressed by cAMP. The inhibitor glycoprotein has been purified and the amino terminal sequence has been determined. The gene coding for this glycoprotein will be cloned by the same techniques used for the cAMP phosphodiesterase gene. A third protein, the cAMP protein kinase will be studied in collaboration with another laboratory and compared to the first two genes. The cAMP dependent protein kinase regulatory and catalytic subunit genes will be recovered from a cDNA library prepared with cAMP induced mRNA and introduced into the lambda vector gt11. Several mutants which lack cAMP phosphodiesterase will be analysed to determine if they are structural or regulatory defects. The role of cAMP dependent protein kinase in the regulation of the other genes will be analysed. The cAMP phosphodiesterase gene will be manipulated in a way which allows its expression and use to degrade cAMP in Dictyostelium and other cells. This should provide a new tool for the study of cAMP metabolism.